A metal-oxide-nitride-oxide-semiconductor (MONOS) memory cell is a type of nonvolatile memory device structure. A MONOS cell generally comprises a semiconductor substrate, a channel layer above the semiconductor substrate, source and drain diffusion regions in the surface of the semiconductor substrate, and a gate conductor above the channel layer. An oxide-nitride-oxide (ONO) layer is disposed between the channel layer and the gate conductor. In the ONO layer, a layer of nitride is sandwiched between two insulative layers of oxide.
In a MONOS memory cell, electric charge is stored in traps in the nitride layer, and this stored charge is utilized to store data. MONOS memory devices provide high stability and reliability.